As a conventional electric motor apparatus for electric power steering, means in which a control unit comprising a metal substrate for installing a heat generation component, a control substrate for installing a non-heat generation component, a circuit case in which insert molding of a conductive plate for wiring and a connector is performed, and a heat sink for dissipating heat of the metal substrate etc. is placed between an electric motor and a speed reduction mechanism and a terminal of the control unit and a winding terminal extending to the control unit side beyond the electric motor are welded in connection of a power supply part of the control unit and the electric motor has been known.
Also, means in which a case for attaching a driving circuit and a control circuit is placed between an electric motor and a worm side case and in connection of a power supply part of a circuit substrate and the electric motor, an ECU lead and a brush lead extending from the electric motor to the case side are soldered and the connection is locked by a conductive fixed spring has been known.
In both the structures, a shaft extending from the electric motor to the speed reduction mechanism through the control unit is attached and it is coupled to the speed reduction mechanism through the shaft.
In a general electric motor apparatus for electric power steering including the configuration described above, the best assist with respect to steering of a steering wheel of a driver is performed by driving the electric motor based on signals of a vehicle speed sensor for detecting a travel speed of a vehicle and a torque sensor for detecting steering torque of the steering wheel.
In these electric motor apparatuses for electric power steering, by integrating the electric motor with the control unit, the whole apparatus is miniaturized and also a length of electrical wiring for making electrical connection between the electric motor and the control unit can be minimized and noise, power loss, cost cutting, etc. by a decrease etc. in material cost can be reduced.
[Patent Reference 1] JP-A-2002-120739
[Patent Reference 2] JP-A-2004-135492